Animal welfare

Genetic determination of positive and negative social behavioural traits in pigs

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Abstract

Introduction The objective of this study was to quantify the genetic basis of social behaviours in pigs and assess their correlations to identify traits suitable for selection. Most pigs experience injuries from harmful social behaviours such as aggression and tail-biting, but economic constraints limit adoption of management-based solutions. Selective breeding offers a sustainable route to improvement, yet social behaviour is complex, positive social behaviours are often overlooked, and desirable social behavioural traits could correlate favourably or unfavourably with negative traits and production. This study explored the genetic determination and correlations between a suite of positive and negative social behaviours. Material and Methods Pigs were housed on a commercial crossbred evaluation farm (Iowa, USA). Experimental animals were genotyped using the Porcine 50K SNP chip, and sires were whole-genome sequenced. Two batches of pigs (n=2341 weight (mean±SD): batch 1, 21.07±4.38kg, batch 2, 41.78±11.41 kg) were housed in mixed-sex pens under standard commercial conditions and all pigs were tail docked. Social behaviours recorded by continuous observation (30 min per pig) were damaging agonistic, non-damaging agonistic, tail manipulation, ear manipulation, belly nosing, social play and gentle nosing. Pigs' behavioural response to the sound of another pig vocalising during play or when distressed (handled) assessed their receptivity to positive/negative emotions of others (emotional contagion). Fresh skin lesions were counted (anterior, central and caudal) 24h after group formation (injuries from establishment of dominance relationships) and 7d later (new injuries from chronic aggression). Anterior and central skin lesions indicate involvement in reciprocal aggression, whilst rear lesions indicate receipt of non-reciprocal aggression. Genetic parameters were estimated using linear mixed models in R (sommer package), with fixed effects (sex, weight) random effects for animal identity (pedigree A-matrix) and pen (nested within building and batch).ResultsWe found a high correlation between skin lesions received across body regions 1d post-mixing (anterior-middle rs=0.655, pImplications This study creates a unique dataset and provides the first quantitative and genetic characterisation of a broad suite of social behavioural traits in pigs. It will identify suitable target traits for selection to improve welfare and productivity, supporting sustainable improvement across diverse production environments.

Keywords: 2026

How to Cite:

Oldham, L., Lee, V., Nguyen, T., Brims, M., Jack, M., Kadlecova, A., Roehe, R., Arnott, G., Lewis, C., Lima, G., Seddaiu, P., Spath, I., Rutherford, K., Lawrence, A. & Turner, S., (2026) “Genetic determination of positive and negative social behavioural traits in pigs”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286888. doi: https://doi.org/10.31274/wcgalp.24157

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